Indian Council of Medical Research (ICMR), India's one of the apex medical bodies said it had validated IgG Elisa kits of three companies, as government steps up efforts to conduct sero-survey to measure COVID-19 exposure in the vulnerable population like healthcare workers, frontline workers and people living in containment zones.
ICMR validated test kits of Zydus Cadila, Germany-based Euroimmun and US-bsed Calbiotech. Zydus had licensed the COVID Kavach Elisa IgG test kit developed by ICMR. The medical research body had earlier claimed that its test kit has an impressive 100 percent specificity and 98 percent sensitivity.
The IgG Elisa test kit helps in detecting immunoglobulin class G antibody in the blood samples and determine who had previously been infected with COVID-19 and may have developed an immunity.
Depending upon the level of seroprevalence of infection, matching public health interventions can be implemented for prevention and control of the disease.
To know more about sero-survey and how it helps in the fight against COVID-19, please read the explainer here.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
ICMR hasn't provided the details about the diagnostic sensitivity and specificity of Euroimmun and Calbiotech test kits. The Calbiotech has claimed that its IgG test kit has sensitivity of 98.3 percent and specificity - 98.1 percent.
Euroimmun test has 99 percent specificity and 100 percent sensitivity after 21 days, following the onset of symptoms.
Sensitivity is the percentage of persons with the disease, who are correctly identified by the test, and specificity refers to the percentage of people without the disease who are correctly tested negative or excluded by the test.
Both Euroimmun and Calbiotech test kits have emergency use authorisation approval from USFDA.
High accuracy is extremely crucial to correctly estimate the prevalence of COVID-19 infection in the population.
ICMR said IgG ELISA or CLIA tests which are USFDA-approved can be used directly after due marketing approval from DCGI.
ICMR is depending on Elisa IgG test kits that are more accurate than rapid antibody test kits. The government earlier attempt to do a nationwide sero-survey, had to be shelved after it found that the imported Chinese rapid antibody test kits had accuracy issues.
This time, ICMR said that the test kit it has developed undergone intense validation in three stages and has been found to have high sensitivity and specificity.
To fast track production and increase availability of the IgG ELISA test, ICMR has transferred this technology to seven companies such as Zydus Cadila, J Mitra & Company, Meril Diagnostics, Voxture Bio, Trivitron Healthcare, Karwah Enterprises, Avecon Healthcare, etc.
The technology has been transferred to various entities without an exclusivity clause.